Abstract: Power electronic transformer (PET), which can realize transformation of multiple voltage levels and electrical energy forms, has become the core equipment of flexible distribution network. This paper introduced the key technology and prospects of the electromagnetic transient (EMT) equivalent modelling and fast simulation of various types of PET. First, the urgent challenges of the EMT simulation of PETs were summarized by comparing with the equivalent modelling algorithms of the HVDC modular multilevel converters (MMC). Then the equivalent modelling framework of the PET was given. Taking the dual active bridge (DAB) converter as an example, three equivalent models (EM) using port decoupling, preprocessing of node admittance matrix and conversion of multiple port parameter matrix were analyzed. Through simulation comparison, the advantages and disadvantages and applicable scenarios of the three models were pointed out. Finally, the research direction of PET equivalent modeling and real-time simulation was prospected.